The Paducah Gaseous Diffusion Plant (PGDP) is located in Western Kentucky, about 10 miles west of the City of Paducah. It currently employs approximately 1700 workers; some 8,000 individuals have worked at the plant since it was opened in 1952. The plant is in a rural area and some areas adjacent to the site are protected conservation, wildlife and recreation areas. The primary function of the PGDP has been to produce enriched uranium for use by commercial reactors or as feed material for other plants that further enrich the uranium. Workers, government officials and the surrounding community have raised concerns about potential health effects from current and past exposures at the plant. The proposed studies will develop new information to help address these concerns. These investigations will take a two-pronged approach, evaluating the impact of historical exposures on worker mortality, and characterizing the effects of more recent exposures on current and future risk of disease. The specific aims of this feasibility study are: AIM 1: Carry out site visits to the PGDP facility in Paducah and to Oak Ridge, in order to initiate direct communications with these two important sources of records and other information.AIM 2: Develop and refine a panel of biomarkers to assess exposure and tissue response to radiation at PGDP, including: Chromosome Aberrations; Somatic Mutations; and Protein Adducts.AIM 3: Develop and validate systems and procedures to procure, transport and test biological samples from PGDP workers.AIM 4: Identify current PGDP workers with higher and lower levels of exposure. The overall purpose of this study is to assess the feasibility of undertaking a comprehensive investigation of both historical exposures that may have affected the health of PGDP workers and more recent exposures that may affect current and future disease risk.